C++ :: Which Object Draw Is Being Called In Case Of Pointer Pointing To NULL
Apr 12, 2013[URL] ....
Which object's draw is being called?
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C++ :: Pointer Pointing To Null Still Executing
Dec 9, 2013in the below program for both class pointers pointing to null. Class contains normal function executing but class contains virtual function getting segmentation fault.
#include <cstdio>
using namespace std;
class A
{
[Code].....
C++ :: Pointing To NULL And 0 The Same Thing?
Apr 13, 2014Is:
char *endp = NULL;
the same thing as:
char *endp = 0;
?
C++ :: check Pointer To Class Object For Null Value?
Feb 14, 2013lets say I have a pointer p_unit of type c_unit* (c_unit is an a.b.c.)
I have a function that returns a pointer to a new c_unit object:
c_unit * man_add_unit() {
c_unit * local_p_unit;
unsigned short int local_run_code;
print_man_add_menu();
local_run_code = get_a_run_code(); // this bit just gets user input
switch (local_run_code)
[code]....
I assign that to p_unit, then add it to a vector v_units:
p_unit = man_add_unit();
v_units.push_back(p_unit);
cout << "New unit added.
";
The whole program runs on a loop, and another thing the user can do is to print out data on c_unit objects pointed to by v_units. The problem is, in that function up there ^ I give the user the option to go back to main menu without creating a unit.
Since "local_p_unit" is declared but not assigned an initial value, I'm guessing the function would return a "null" pointer (which is what's hanging me up). If I just let this run with the above code, and go to print out the unit data, the program crashes.
I tried to make an if thing with p_unit == 0 but this always returns false and doesn't catch the "bad" unit that will subsequently cause a crash.
Btw, I have considered assigning a reference to a generic c_unit object to that there local_p_unit so it won't return null, then remove pointers to that object from v_units at the end of the loop.. But I know there's got to be a better way.
C/C++ :: Destructor Called Just After Declaring Object?
Jan 29, 2015Why does the destructor is called just after declaring my object?
// MAIN
int main(void) {
Jucarie j1;
Jucarie j2(j1);
return 0;
}
THE DESTRUCTOR
Jucarie::~Jucarie() {
cout << "Destructor called" << endl;
delete[] material;
material = NULL;
}
I do not have a copy constructor, i just want to use the shallow copy. Why i get Debug Assertion Failed error? If i delete the destructor, all work fine.
I get it, the problem occurs when the material from j1 is deleted right? Because it has already been delete by j2.
C# :: Getting Instance Object Is Null Compile
Dec 2, 2011Code:
public class ColorGenetics
{
public static hk1Class jw;
public static linkedClass link;
}
[code]...
Code builds fine but compiler says I tried to use bject link w/o providing an instance. Class linkedClass has an instance of Class hk1Class set to var jw1.I had linkedClass useing the same var jw for the object instance. I changed it to jw1 thinking that would clear it up and it didn't.
C++ :: Object Inside Class Becomes NULL?
Nov 18, 2013I have built LOG4CXX lib and DLL and trying to use it in my application
Loh.h
class Log
{
public:
[Code].....
In my main I am initializing Log class object and calling Debug method to log debug message to a file.
Issue I am facing is at if(CLogger::oLogger != NULL) which is always returning oLogger as NULL.
C++ :: Pointers To Automatically Null When Object Is Deleted
May 18, 2013Say I have an object and 10 pointers to it in several other objects of varying class types. if the object gets deleted, those pointers have to be set to null. normally I would interconnect the object's class with the classes which have pointers to it so that it can notify them it is being deleted, and they can set their pointers to null. but this also has the burden that the classes must also notify the object when THEY are deleted since the object will need a pointer to them as well. That way the object doesn't call dereference a dangling pointer when it destructs and attempts to notify the others.
Auto pointers and shared pointers are not what I'm looking for - auto pointers delete their object when they destruct, and shared pointers do the same when no more shared pointers are pointing to it. What I'm looking for is a slick method for setting all pointers to an object to null when the object destructs.
C++ :: Pointer As Parameter Is Null?
Apr 9, 2014In my raytracer-project I have the following function:
bool hitObjects(Ray &ray, std::vector<Object *> &objects, Vector3& normal, Material *mat) {
double tmin = K_HUGE_VALUE;
double t;
[Code]....
When I try to run this, I only get the message "Material pointer is null". So, somehow the pointer is null after the hitObjects-function is called, even though it isn't inside that function.
C/C++ :: Initializing Pointer To NULL?
May 17, 2014So I'm writing a small program for class, and for some reason I keep getting an error when trying to initialize head to NULL. Even threw in the namespace just to see, nothin'.
#ifndef NUMBERLIST_H
#define NUMBERLIST_H
using namespace std;
[Code].....
There's my header file. Not sure what I'm doing wrong with the constructor.
EDIT: Got it to work with nullptr, but still curious why that isn't working
C++ :: Create Null Pointer After Using Delete
Aug 7, 2014In jumping into C++ it says something like this: It's not necessary but when you delete a pointer it's a good idea to reset it as a null pointer. That if your code try's to dereference the pointer after being freed, your program will crash. This happens to a lot of experienced programmers.
This could corrupt users data. delete p_int;
p_int = NULL;
1. If you can deference a pointer after the memory is freed, why can't you just delete the pointer?
2. If you can do 1, how do you delete the pointer using code?
3. Every thing I've read says that free memory is handed out in a sequenced order. I don't believe that is true at all. I may be wrong. Why can't you put the data in any number of places if it will fit. Isn't the compiler smart enough to know where bytes (bits)and pieces are stored?
4. If you storing anything in free memory must use a pointer to it?
5. Can a pointer or something similar be used with stack memory?
C++ :: Null Destination Pointer Exception
Aug 26, 2014Here when NonlinearSolver called the constructor,
m_gradient() constructor is called to construct m_gradient, which in turns sets a variable called m_S to NULL(0), then in the assignment operator, because the m_S is NULL, Visual Studio throws an exception saying that destination pointer is null, but it's not fatal. I don't like that to happen because I have to press ignore many many times when the program is debugged, how can I fix this bug (not mine) to avoid the null destination pointer exception?
As an intermediate layer, the function calls boost unbounded array operator = which in turns calls std::copy which results in this error
Code:
NonlinearSolver(solver_type const & solver)
: m_gradient()
, m_function()
, m_projection() {
*this = solver;
[Code] .....
C++ :: Transverse Vector Of Structs - Null Pointer
Mar 14, 2014struct mystruct{
int n;
};
class mscope{
public:
std::vector<mystruct> mv;
[Code] .....
So I have a vector of structs and I want to traverse it, find a struct that matches a constraint and obtain a pointer to that struct. I made a function for this purpose which takes a number and an empty pointer that will store the reference. However, after function returns the pointer becomes null. What could be causing this?
C++ :: Getting Invalid Null Pointer Error Message After Successful Build
Jan 22, 2013getting an invalid null pointer error message after a successful build. This program is supposed to ask for firstName, lastName, age and maJor and keep doing so until the age that is input is 0 and then the program closes. Here is what I have.
#include <iostream>
#include <string>
using namespace std;
[Code]....
C++ :: Calling Defined Function Pointer From Another Pointer To Class Object?
Aug 19, 2014I am attempting to implement function pointers and I am having a bit of a problem.
See the code example below; what I want to be able to do is call a function pointer from another pointer.
I'll admit that I may not be explaining this 100% correct but I am trying to implement the code inside the main function below.
class MainObject;
class SecondaryObject;
class SecondaryObject {
public:
[Code]....
C# :: Action Object - Create New Action When Function Is Called
Dec 3, 2012consider this code:
Code:
private void DoIf(bool b, Action f)
{
if (b)
f();
}
int x = 0;
bool no = false;
DoIf(no, () => x = 10);
Does the compiler emit code to create a new action when the function is called or only when f() is actually called?
C :: How To Get Upper Case And Lower Case Equal
Feb 18, 2015I just dont know how to get my upper case and lower case equal...heres the program: Write a program to calculate utility cost for ACME UTILITY COMPANY. The company has 3 types of customers (R) residential, (C) Commercial and (G) government. Customers are billed based on the number of kilowatts used and they type of customer they are (R,C,or G).
Residential cusstomers are charged 0.25 cents per kilowatt hour for the first 500kw used, and 0.35 cent per kwh for all kw used over 500.Commercial customers are charged 0.22 cents per kilowatt hour for the first 999kw used, 0.29 cents per kwh for all kw used over 999 kw up to 1999 and 0.45 cents per kwh for all kilowatts used greater than 1999. Commercial customers that use over 2000 kw are charged a special surcharge of 100.0 in addition to the regular charges.
Government customers are charged 0.34 cents for the first 1500 kwh used(<=1500). 0.30 cent for the next 1000 kwh(1501-2500) and 0.25 cents for all kwh used over (>=2501)
in addition residential customer are charged .5% tax on the cost utilities while Commercial customers are 5% tax on the cost of utilities not including the special surcharge Government customers are not charged a tax
Code:
#include <stdio.h>
#include <math.h>
int main(void)
{
int R;
int ct;
int kwh;
int taxes;
int surcharge;
int charge
}
[code].....
the program should quit with Q and calculate the amount owed, utility charge, and surcharge
C++ :: Calling Constructor From Constructor Set Pointer To Null
Jan 25, 2014VS 2012 / Windows 7 64 bit
class
class myclass {
public:
myclass(){/*stuff here*/}
myclass(int* p) {MyPointer = p; myclass()}
[Code] ....
it works until the myclass(int* p) calls myclass()
then the MyPointer will become CCCCCCCC (NULL value)!
is there a way to stop the second constructor from resetting the pointer value to null?
C++ :: Null Terminator Same As Null And Through False Value?
Feb 18, 2014I am looking at one of the functions of an exercise:
void escape(char * s, char * t) {
int i, j;
i = j = 0;
while ( t[i] ) {
/* Translate the special character, if we have one */
switch( t[i] ) {
[code]...
Notice the while loop evaluates the current value in t to true or false. When we hit the null terminator, does that get evaluated as 0 and hence evaluates as a falsy value so the while loop exits?
C++ :: Two Dimensional Pointer To Object?
May 24, 2012I am migrating a scientific code from Java to C++.
What's wrong with the two functions? I can use the int** like a two dimensional array but not the Agent**.
I receive this error: "No operator = matches this operand".
(I have allocated two dimensional arrays for objectSpace and agentSpace somewhere else).
Code:
int** objectSpace;
Agent** agentSpace;
void Space::removeAgentAt(Point p) {
agentSpace[p.x][p.y] = NULL;
}
void Space::putAgentTo(Agent agent, Point newP) {
agentSpace[newP.x][newP.y] = agent;
}
C++ :: Pass Object As A Pointer In Function
Apr 12, 2013i need to pass myboard.board (board is in the class Cboard and it is an array of int) to a function in a class called piece however this is troubling . i need to pass it as pointer os that i could change its value here under is my code.
main.cpp Code: #include<iostream>
#include"board.h"
#include "pieces.h"
[Code].....
C++ :: Pointer Class Object Vectors
Aug 4, 2013#include <iostream>
#include <vector>
#include <string>
#include <map>
using namespace std;
struct bop {
string realname; //real name
[Code] ....
Okay, so first thing's first. The program will not compile due to lines 39-45. If I were to change those pointers into regular objects, it will not change the values of my class object. So what is the right way to do this?
I want the user to be able to input the # of employers/programmers into the system. But I cannot do that with an array of classes because when declaring an array; the array size must be constant.
C++ :: Convert Pointer To Plain Object
Jul 23, 2013I have pointer object and i have to assign to another variable ( new object ). But if i change any value in new object should not reflect in old object. I did in the below way, it changes the value.
class Test {
public:
int num;
};
Test* obj;
obj.num=1;
Test obj_n=*obj;
obj_n.num=2;
Now both object's num have value as 2;
i.e
obj.num // has 2
obj_n.num // has 2
Actually my expected result is:
obj.num - should have value 1
obj_n.num - should have value 2
My actual scenario is different where Test obj is pointer object, so obj should be pointer object. i have given sample scenario.
C++ :: Assigning Address To Object Pointer
Aug 16, 2013I have the following code.
StackElement *StackElementArray;
StackElementArray = new StackElement[iMaximumDepth];
I want to assign one element of this array StackElementArray the address of another object. For example,
voidStackMem::push(StackElement &iStackElement) {
CurrentDepth++;
StackElementArray[0] = iStackElement;
}
The StackElement class contains pointers to some dynamic arrays. When I use the assignment, StackElementArray[0] = iStackElement;, it doesn't copy the complete contents and I have to define an 'assignment operator' function to copy all the contents. I am wondering if there is a way I can assign StackElementArray[0] the pointer to the StackElement object. In that case, I will not need to copy the contents of iStackElement into StackElementArray[0] and will just copy the address.
C++ :: Function Pointer With Object As Parameter?
May 30, 2013I'm making a code that uses a Function pointer. The problem is, when I try to compile appears an error like:
error: no matching function for call to 'rnVector::rnVector()'
Here's part of the code:
phiFunction::phiFunction(double (*f)(rnVector), rnVector (*df)(rnVector)) {
//... Here comes the code stuff...
}
C++ :: Passing Object By Pointer To Function?
May 20, 2014I have a Qt classes as follow:
Code:
class Vehicle {
public:
void AddData(QString str, Data* data) {
_myDataMap.insert(str,data);
} virtual void Init();
[code].....
My questions are:
After the main function called d1->Modify; the data stored in _myDataMap will get modified too.
What is the more appropriate way of passing the Data through AddData in such case?
If i do AddData(const Data & data), i will not be able to use inheritance of Data, i.e passing a subclass of Data to AddData.